These effects are due to "pyrethrin" contained in the plant, which is an acid fixed resin; also there are present a second resin, and a yellow, acrid oil, whilst the root contains inulin, tannin, and other substances.

The best products for elimination of fleas outdoors are formulations that contain a knockdown material such as pyrethrin or permethrin plus an insect growth regulator (pyriproxyfen or methoprene) to inhibit larval maturation.